The Last Ten Feet: Where Water Goes

Search for gutter companies in St. Louis and you will find a great many pages about seamless aluminium, colours, guards and free estimates. Search for where the discharge should actually go and the market goes quiet. Some of the results are not even in Missouri.

That gap is strange, because the trough is the cheap part of the problem and the last ten feet is the expensive part. Gutters that overflow ruin a walkway. Water put down beside a foundation for a decade ruins something considerably more expensive than a walkway.

What the last ten feet has to achieve

One thing: get the water past the backfill zone and onto ground that carries it away.

The backfill zone is the ring of disturbed soil around the foundation, put back after the house was built. It is looser than the undisturbed ground around it, so it drains faster, which sounds good and is not. Water preferentially finds that loose ring and travels down it, straight to the footing. Around a basement this is sometimes called the bathtub effect, and it is the reason a downspout at the wall matters so much more than the same volume of water landing twenty feet out in the yard.

Figure 2 · Same roof, same rainfall, same downspout. The only variable is what happens in the last ten feet. In A the water is put back exactly where the footing is; in B it is carried past the backfill zone and let go on grade where it can leave.

The options, worst to best

Nothing. The downspout ends at the elbow and the water lands on whatever is there. You can identify these from the street: there is a scoured pit under the elbow, or a dead patch of grass, or a splash line up the siding or brick. This is not a maintenance problem, it is an unfinished installation.

A splash block. A concrete or plastic tray under the elbow. It stops the water digging a hole, which is worth something, and it moves the discharge point roughly eighteen inches. Eighteen inches is not out of the backfill zone. A splash block is erosion control, not drainage.

A short extension. Better. Four to six feet of pipe or a hinged extension gets the discharge to the outer edge of the backfill on most houses. The two problems are practical rather than technical: extensions get in the way of mowing, so they get flipped up and left up, and they get kicked out of alignment, so they discharge at the joint instead of at the end.

A long extension onto graded ground. Good, when the ground actually falls away from the house. If it does not, you have moved the puddle ten feet and it will run back.

A buried line to daylight. The proper answer where the site allows it. The discharge is carried underground, past the backfill zone, and released on grade somewhere down the slope. Nothing to mow round, nothing to kick, nothing visible. Detail here.

Say the unflattering thing

Grade beats everything, and grade is not our trade

If the ground around your house slopes towards the house, no downspout arrangement will fully save you, because the whole yard is delivering water to the wall and your roof is only part of the total. Sometimes the correct advice is to spend the money on regrading and to leave the gutters alone. That work is landscaping and excavation, not roofing, so it is not work Keys sells, and we will still tell you when it is the real answer.

Where a discharge should not go

Onto a neighbour's ground. Concentrating your roof onto somebody else's yard is a good way to have a bad relationship, and it can be a legal problem as well as a social one.
Onto a driveway or a walk that slopes back towards the house. Very common, easy to miss, and in winter it makes ice exactly where people walk.
Into a window well. Sounds absurd, happens regularly, usually because an extension got moved.
Into a footing drain or a sump discharge, without thought. Combining roof water with the drain that is supposed to relieve groundwater pressure can overwhelm it in exactly the storm you needed it in.
Into the sanitary sewer. Not acceptable practice and generally not permitted. If you have an old direct connection in an older St. Louis property, that is a conversation to have with your municipality and with a plumber, not something to extend.

Every downspout on your house ends somewhere. On most houses nobody living in the building has ever said out loud where. That is the question we ask on every gutter job, and it is the one usually met with a pause: where does this one end up.

The five minute audit you can do yourself

Wait for a decent rain and then go outside with an umbrella, which is the single most useful diagnostic tool in home ownership. Walk the perimeter. Look at every downspout. Where is the water going, right now, while it is happening. Is it running away, standing, or running back towards the wall. Is there a splash pattern up the brick. Is the mulch washed out on one side of a bed. Is there a stripe of silt on a walk pointing at the house.

Then go into the basement and look at the wall on the same side. Damp corners, efflorescence, a musty smell concentrated in one bay: these have a direction, and the direction usually points at a downspout.

Why Keys does this at all

Because a roofing company that reroofs a house, hangs beautiful gutter, and leaves the discharge splashing at the footing has done competent work and left the homeowner with the same problem they started with. The roof and the last ten feet are one system. Keys does downspout reroutes, extensions and underground drainage as part of the same conversation as the roof, which in this market is uncommon enough to be the reason this site exists.

The last ten feet, which is the part nobody sells